Really nice and beautiful game. Liked it.
Indeed the fights are not clear. For a moment I thought my attacks were doing nothing. Until I tried to attack many times in a row. Maybe change the texture of the enemy to show that he is damaged? or tint him red for a moment when you hit him to show that it hits him? Or any other visual code.
Also, the dungeon is a vast labyrinth. After a while the slowness of the character is a bit frustrating. Maybe the powerups could increase the speed of rotation and movement as well?